Abstract

Objective
To determine the effect of oestrogen treatment on
attenuating the growth of tall girls after adjusting for error in height
prediction.
Design
Retrospective cohort study.
Patients
Tall girls assessed by Australian paediatric endocrinologists
between 1959 and 1993. A total of 279 girls received oestrogen treatment
(diethylstilboestrol or ethinyl oestradiol) and 367 girls were
assessed but not treated.
Measurements
Estimated mature height (EMH) was calculated
using radiographic assessment of bone age in adolescence. Final
adult height was self-reported at follow-up. To control for error in
the EMH predictions and their different distributions by treatment
status, pairs of treated and untreated girls, matched on EMH within
1 cm, were selected for analysis. Covariate adjusted estimates of
treatment effect (final height – EMH) were calculated.
Results
In the sample of 108 matched pairs, the mean difference
between the final height and EMH was –1·4 cm (SE 0·29) in the
treated group and 1·1 cm (SE 0·23) in the untreated group, giving
an unadjusted treatment effect of –2·5 cm (95% CI –3·2 to 1·8). A
regression model based on 107 pairs of treated and untreated girls
contained a significant interaction between bone age at treatment
initiation and treatment, which estimated an approximately 1 cm per
year decrease in treatment effect. The treatment effect was greatest
in those commencing treatment at an early bone age and was
significant if initiated before a bone age of 15 years.
Conclusions
On average, oestrogen treatment resulted in an adult
height that was less than predicted. Although treatment was more
effective in the least mature girls, the mean height difference was
relatively modest for most treated girls.